Rex says
The fast lane for the math you almost remember from school. Type the numbers, get the answer, move on with your day.
Try a scenario
Click to load — tweak from there.Inputs
Result
Reorder point
1,860
Expected demand during lead time
1,440
Days until on-hand hits reorder point
0.0
Order now? (1=yes, 0=no)
1
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How to use this
- 1Enter average daily demand (units).
- 2Enter lead time (days).
- 3Enter safety stock (units).
- 4Enter current on-hand inventory (optional) (units).
- 5Read your reorder point on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
The reorder point is the on-hand-plus-on-order inventory quantity at which you must place a new order to avoid stocking out before the replenishment arrives. It's simply the demand you expect to consume during lead time, plus a safety stock buffer for variability. Get this number wrong on the low side and you stock out before the next shipment lands; too high and you're carrying excess inventory and tying up warehouse space and cash. This calculator computes the reorder point from average daily demand, lead time, and a safety stock figure (which you can generate with the companion safety stock calculator), then shows how many days of cover that reorder point represents so you can sanity-check it against your actual replenishment cycle.
Worked example
Using the values the calculator loads with:
Inputs
- Average daily demand: 120 units
- Lead time: 12 days
- Safety stock: 420 units
- Current on-hand inventory (optional): 1800 units
Results
- Reorder point: 1,860
- Expected demand during lead time: 1,440
- Days until on-hand hits reorder point: 0
- Order now? (1=yes, 0=no): 1
What each field means
Inputs
- Average daily demand (units)
- The average daily demand used in the calculation, measured in units. Starts at 120 units so you have a working example on load.
- Lead time (days)
- The lead time used in the calculation, measured in days. Starts at 12 days so you have a working example on load.
- Safety stock (units)
- The safety stock used in the calculation, measured in units. Starts at 420 units so you have a working example on load.
- Current on-hand inventory (optional) (units)
- The current on-hand inventory (optional) used in the calculation, measured in units. Starts at 1800 units so you have a working example on load.
Results
- Reorder point
- Returned as a whole number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Expected demand during lead time
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Days until on-hand hits reorder point
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Order now? (1=yes, 0=no)
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Is reorder point the same as safety stock?
No. Safety stock is only the buffer portion for variability; the reorder point is the full trigger quantity, which equals expected lead-time demand plus that safety stock buffer. People often confuse the two and set their purchasing trigger to the safety stock number alone, which guarantees a stockout under average conditions.
Should I use lead time from the PO date or the order confirmation date?
Use PO submission to physical receipt at your dock, including any inbound transit and receiving/putaway delay before the stock is sellable. Using only the supplier's manufacturing lead time and ignoring freight transit is the most common way reorder points end up too low.
What if demand isn't steady — it's seasonal?
Recalculate average daily demand using only the season you're heading into, not a trailing 12-month average that blends peak and trough. A single annual-average reorder point will underorder ahead of peak and overorder ahead of trough every single cycle.
How often should reorder points be recalculated?
Monthly for A-items with volatile demand, quarterly for B-items, and semi-annually for stable C-items is a reasonable cadence. Any time lead time shifts meaningfully — new supplier, mode change from ocean to air, new distribution point — recalculate immediately rather than waiting for the scheduled review.
Accuracy and limitations
- Results are rounded for display; the underlying calculation keeps full precision.
- Very large or very small inputs may hit floating-point limits in the browser.
- Inputs outside the accepted range are clamped rather than rejected.
Related tools
Safety Stock Calculator (Service Level)
Statistical safety stock from demand variability, lead time, and target service level.
EOQ & Carrying Cost Calculator
Order quantity that minimizes total ordering + carrying cost.
Inventory Turns & Days Sales of Inventory Calculator
Turnover ratio and days-of-supply from COGS and average inventory.
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Reorder Point Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/reorder-point-safety-stock-3pl
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/reorder-point-safety-stock-3pl" target="_blank" rel="noopener">Reorder Point Calculator — RevenueLab</a> (2026).</p>
Source: [Reorder Point Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/reorder-point-safety-stock-3pl) (2026).